Seed Processing, Drying and Storage
Seed Processing, Drying and Storage
This domain tests the post-harvest chain: receiving, cleaning, grading, treating, drying, bagging and storage. Questions often ask for safe moisture, drying calculations, storage conditions and the order of operations.
Processing sequence and drying
- Receive and identify each lot; never mix lots.
- Pre-clean to remove straw, stones and broken seed; then clean and grade to remove inert matter, weed seed and undersized seed.
- Treat seed only after cleaning, with the correct dose and a dye marker where required.
- Dry to the safe moisture for the crop and package in clean, labelled bags.
- Store in cool, dry, ventilated conditions; control rodents, insects and moisture.
Safe moisture is crop-specific: orthodox seed can be dried, recalcitrant seed cannot. High-temperature drying can crack seed coats and reduce germination.
Worked example
A lot weighs 1,000 kg at 18% moisture (wet basis) and must be dried to 12%. Dry matter = 1,000 × (1 − 0.18) = 820 kg. Final weight at 12% = 820 ÷ (1 − 0.12) = 931.8 kg. Water removed = 1,000 − 931.8 = 68.2 kg.
Traps that cost marks
Using a simple percentage subtraction on wet weight; drying before cleaning; mixing wet and dry lots; storing without ventilation; and assuming all seeds tolerate drying.